Silkworm Smuggling (c. 552): How Byzantium Got the Secret of Silk

Around 552, according to the Byzantine historian Procopius, a group of monks smuggled silkworm eggs from Asia to Constantinople and presented them to Emperor Justinian I. The episode is often described as the first recorded case of industrial espionage. It allowed the Byzantine Empire to begin producing its own raw silk, breaking part of a long dependence on Persian middlemen and laying the foundations of one of the most prestigious luxury industries of medieval Europe.

Background: silk, Persia and Rome

Silk had reached the Mediterranean since Roman times along the caravan routes later called the Silk Road (see Zhang Qian’s mission). The technique of rearing the silkworm, Bombyx mori, on mulberry leaves and unreeling its cocoons was developed in China and had spread to parts of Central Asia, but it remained unknown in the Roman world.

By the sixth century, almost all raw silk bound for Byzantium passed through the Sasanian Persian Empire, Rome’s great rival. Persian merchants could set prices, and wars could cut supplies. Justinian tried several remedies. Around 531 he asked the Christian kingdom of Aksum in Ethiopia to buy silk in India and ship it via the Red Sea, but the Aksumites could not compete with Persian traders already established in Indian ports. He also tried to fix silk prices by law and placed much of the trade under imperial control, which Procopius criticised in his Secret History.

What Procopius says

The main account appears in Procopius’s History of the Wars, in the book on the Gothic war (see Gothic War). Some monks arriving from India told Justinian that they had long lived in a country called Serinda, beyond many Indian peoples, and had learned how silk was made. They explained that the silk came from worms, which could not be transported alive, but that their eggs could.

Justinian promised a large reward. The monks returned to Serinda, collected eggs and brought them back to Byzantium. There, Procopius says, they hatched the eggs by covering them in dung to keep them warm and fed the young worms on mulberry leaves. Procopius presents the story briefly and without dramatic detail.

A later writer, Theophanes of Byzantium, whose work survives only in a summary by the ninth-century scholar Photius, tells a different version. In his account a Persian brought the eggs from the land of the Seres hidden in a hollow walking stick. The two stories may describe the same event in different ways.

Where was Serinda?

The location of Serinda is one of the puzzles of the story. The name seems to join Seres, the Greek name for the silk-producing people of the East, with India. Scholars have suggested Khotan, an oasis kingdom in the Tarim Basin that already practised sericulture, Sogdiana around Samarkand, and other regions. Chinese and Tibetan tradition also tells of silkworms being carried to Khotan by a princess who hid them in her headdress, a legend that shows how widely the theme of smuggled silkworms circulated.

Building a Byzantine silk industry

Silk production did not appear overnight. Mulberry trees had to be planted and breeding stocks multiplied over many years. In 568, Turkic envoys led by the Sogdian Maniakh arrived in Constantinople hoping to sell silk directly, an embassy described by the historian Menander Protector. According to Theophanes of Byzantium, Emperor Justin II surprised the envoys by showing them that the Byzantines now bred silkworms themselves.

Over the next centuries sericulture spread in Syria, Asia Minor and Greece, especially in the Peloponnese and around Thebes. Imperial workshops in Constantinople wove the finest fabrics, including purple silks reserved for the emperor and used as diplomatic gifts. The tenth-century Book of the Eparch regulated the city’s silk guilds, and foreign visitors were forbidden to export the most precious grades. In 1147 the Norman king Roger II of Sicily raided Thebes and Corinth and carried skilled silk workers to Palermo, helping silk weaving spread to Italy.

Myths and facts

• Myth: The smuggling ended the Silk Road trade. Fact: Imports continued for centuries, and Chinese silk remained prized; Byzantium simply gained a domestic supply.
• Myth: The monks were spies sent by Justinian. Fact: Procopius says the monks approached the emperor with the offer; he then rewarded them.

Timeline

• c. 531: Justinian seeks Aksumite help to buy silk without Persian middlemen.
• c. 552: Monks bring silkworm eggs to Constantinople, according to Procopius.
• 568: A Turkic embassy led by Maniakh visits Constantinople to offer silk.
• 10th century: The Book of the Eparch regulates Constantinople’s silk guilds.
• 1147: Roger II of Sicily carries silk workers from Thebes and Corinth to Palermo.

Why it matters

The smuggled silkworm eggs gave Byzantium control of a strategic luxury product. Byzantine silk became a tool of diplomacy and display for some 600 years, and the transfer of sericulture began its long journey into Western Europe.